The software giant said the new 6.5 handsets will be "Windows phones," with clear branding to appeal to users familiar with the company.

"We discovered that most people who carry a Windows phone don't realize it's running Windows Mobile," Stephanie Ferguson, general manager for Windows Mobile product management, wrote in a blog post. "We also heard from many people considering their very first smartphone purchase that they'd very strongly consider a phone running Windows because it's a brand they know and trust.

"You'll see us try to simplify our branding so it's easier for people to know when they're carrying a Windows phone and easier to find them in stores," she said.

Ferguson added that the new Windows phones are the first smartphones running Windows Mobile 6.5, which has an improved user interface, better Internet browsing capability and access to the new Windows Marketplace, the company's online store for mobile apps.

She went on to say that an informal survey conducted by Microsoft found that about 15 million U.S residents plan to buy a new smartphone in the next year, with 74 percent listing productivity as their most desired feature.

"We took this feedback to heart, making the user interface more touch-friendly and improving notifications and updates from e-mail, text and calendar items," Ferguson said in the blog post. "On Oct. 6th, you'll see new Windows phones with or without keyboards, with or without touch screens, as well as your choice of GPS, accelerometer and high resolution camera."

The news of Microsoft's push into the lucrative mobile sector comes as key industry players release significant upgrades to their respective operating systems along with major handset launches.

Nokia (NYSE: NOK) is holding a conference tomorrow at which it will announce details about a new mobile Internet device, the N900, running on its new open-source platform Maemo 5, and may unveil a Maemo smartphone aimed at the iPhone.

In June, Palm (NASDAQ: PALM) introduced the Pre, based on its webOS software. The handset maker is also ramping up an app store called Palm Catalog and is expected to release more webOS handsets in the fourth quarter.

Apple (NASDAQ: AAPL) began selling the iPhone 3GS on June 16, and the next day upgraded the iPhone OS to version 3.0, with 3.1 expected out this month. It will also begin selling the iPhone in China as early as next month in a three-year deal with China Unicom.

Meanwhile, Google's (NASDAQ: GOOG) open-source mobile OS Android is expected to gain momentum with a host of handsets coming for the holiday season. For instance, Motorola (NYSE: MOT) is holding a conference Sept. 10 at which it will reveal details about its upcoming Android-powered phones.

Android itself is undergoing an aggressive series of updates. Its first update, dubbed Cupcake, raised Android to version 1.5, and is slated to be soon followed by Donut, version 2.0, and Éclair -- though timing on the future versions hasn't been disclosed.